1. Technical Field of the Invention
The present invention relates generally to Quality of Service (QoS) provisioning in communications networks. More particularly, without limitation, the present invention relates to a QoS monitoring system and method for a high-speed DiffServ-capable network element (e.g., a router) disposed in an autonomous system.
2. Description of Related Art
Driven by the myriad advances in networking technology that are taking place at an unprecedented rate, Internet access solutions and Internet-based applications such as e-commerce have become the mainstay of today's New Economy. Internet service providers (ISPs) and Internet access providers (IAPs), which provide access to the Internet and range in size from small, local operators to national entities offering connectivity and IP-based services nationwide or internationally in some instances, are now as ubiquitous as local hardware stores and compete vigorously for subscribers by offering a variety of pricing plans and variable bandwidth services. Further, an increasing number of prominent national ISPs have begun to offer proprietary services and content in addition to simple Internet access.
Despite the Internet's rapid growth over the last ten years or so, several important considerations remain. For example, because the Internet is a connectionless and stateless network, current Internet-based service implementations can only provide “best-effort” services. That is, whereas the network will try its best to forward user traffic, it cannot provide any guarantees regarding packet loss rate, bandwidth, delay, etc. Thus, packets may be dropped indiscriminately in the event of congestion, path failures, and the like. While this kind of service works fine for some traditional applications (e.g., file transfer protocol or FTP, email, etc.), it is intolerable for the newly emerged real time, multimedia applications such as Internet Telephony, video-conferencing, video-on-demand, Interactive TV (ITV), online music, etc.
Accordingly, it is commonly understood in the communications industry that the cornerstone of future IP network growth will be IP QoS, which provides for a set of service requirements to be met by the IP network while transporting a flow (typically defined as a packet stream from a source to a destination (unicast or multicast)). In other words, QoS is defined as a measurable level of service delivered to network users, which can be characterized by a set of metrics (e.g., packet loss probability, delay, jitter or delay variation, available bandwidth, et cetera). Such QoS can be provisioned by network service providers in terms of a service agreement (e.g., a Service Level Agreement or SLA) between subscribers and providers. For example, a subscriber's requirement can be that for some traffic flows generated by the subscriber, the network should guarantee a path with at least certain bandwidth level.
It should be apparent that by employing different levels of IP QoS, service providers can achieve greater profitability through premium services offered to high-margin business customers, more efficient use of network resources, and higher-priced service levels. In addition, they can be more competitive through enhanced service differentiation, better-than-best-effort service, and customized solutions.
To make a contractual agreement that customers can trust, a service provider needs a network with QoS capabilities and a policy management system to configure, control, and maintain performance levels. Differentiated Services (DiffServ) is an IP QoS architecture defined by the Internet Engineering Task Force (IETF) that has particular reference to the service provider and carrier networks. DiffServ concentrates on aggregating flows and per hop behavior applied to a network-wide set of traffic classes, thereby minimizing the amount of signaling required. Effectively, DiffServ provides a lightweight signaling mechanism between service provider's domain borders and network nodes, carrying information about each packet's service requirements.
Whereas the DiffServ framework provides broad architectural guidelines with respect to the provisioning of IP QoS in a trusted domain, management of traffic flows within an individual DiffServ-capable node is contemplated to be application- and implementation-specific. As a result, there exists a need for solutions that reliably and accurately monitor the traffic behavior within a node and help determine QoS relevant parametric information in order to ensure appropriate levels of service within the DiffServ framework.
Current techniques for monitoring intra-nodal traffic behavior for DiffServ purposes are beset with various shortcomings and deficiencies, however. For example, the existing QoS monitoring schemes typically involve processes with a high granularity of measurements. Thus, the aggregate level traffic behavior (e.g., per port, per class, etc.) is not adequately captured. In addition, where the traffic is segregated into different queues according to some classification, dynamic behavior of such queues is not monitored against service-constraint-based thresholds that may be required for SLA assurance, compliance and analysis. As a consequence, the current solutions cannot provide a reliable measurement of average occupancy of the DiffServ-provisioned queues. Furthermore, parameters that quantify resource-specific behavior such as average under- and over-utilization of the resources (e.g., bandwidth, buffer depth, etc.) are not adequately profiled as well.